An ultrasound test is used to diagnose a low-lying placenta or placenta previa, in which the placenta partially or fully covers the cervix. But ultrasound does not always provide a clear picture of the placenta's location.

Unless an immediate cesarean delivery is planned, a pelvic (vaginal) examination is not done because of the risk of further injuring the placenta, causing heavier bleeding.

Electronic fetal heart monitoring is used to check the fetus's condition.

When an early delivery is needed, an amniocentesis may be done. It is used to find out whether the fetus's lungs are ready to breathe well after birth. For an amniocentesis, a needle is inserted into the mother's belly to take a small sample of amniotic fluid from inside the uterus. This fluid is made by the fetus's lungs. A lab test of the fluid can test for signs that the lungs are well developed.